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<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./ajax/jQuerymini.js"></script>
    <style>
        .first {
            border: salmon solid 1px;
            width: 100px;
            height: 100px;
            background-color: palevioletred;
        }
    </style>
</head>

<body>
    <div class="first">

    </div>
    <script>
        $(function () {
            $('.first').click(function () {
                $(this).slideToggle('slow');
                // $(this).show();

            })
        })
    </script>
</body>

</html>